DESCRIPTION: (Applicant's Abstract) Cigarette substitutes (CS) have been and continue to be developed. Although advertised for smokers concerned about secondhand smoke, many smokers may see these as safer cigarettes and alternatives to cessation. We will determine a) by whom, why and how such substitutes are used, b) whether CS use undermines motivation to stop smoking, and c) whether CS use (+/- cigarette use) produces less nicotine and toxin exposure than cigarettes. One survey and two experimental studies will examine the newest CS: Eclipse. We will survey 400 Eclipse users to determine their characteristics (e.g., level of nicotine dependence), reasons for purchase (e.g., to decrease risks of smoking), pattern of use (e.g., along with vs instead of cigarettes), etc. These users will be compared to 400 smokers who have not used Eclipse to determine who is attracted to CSs. Both groups will be followed for one year to determine whether the incidence of attempts to stop smoking is less in CS users than nonusers. Study 2 will enter 60 smokers interested in using a CS to an A-B-A design of smoking their normal cigarette for 3 weeks, followed by using Eclipse for 12 weeks, followed by a return-to-baseline for 3 weeks. The major dependent variables will be CS and cigarette use, cotinine, CO, SCN, withdrawal symptoms, product ratings, adverse events and vital signs. Whether or not Eclipse itself becomes a commonly used product, CSs are very likely to be marketed in the near future. We believe it imperative to begin studying these substitutes so that, unlike low-tar/low nicotine cigarettes, we will know whether their introduction is good or bad for public health.